It is VERY possible that someone skilled with 3D modeling and what not could create a mesh for Rin's shirt and have it remove her arms. But she'd still "hold" things normally. So, a paint brush or whatever would be floating in midair where Rin's hands should be. Because removing the arms wouldn't be TOO hard if you knew how to mod but getting a character to be able to use her legs as arms would most likely completely impossible. Emi would be easier. Changing her skintone on her legs could be a start but someone better with 3D modeling could create some kind of mechanical legs.

After Act 1 Demo:Rin>>Hanako>>Shizune>>>>Lilly>>>>>>>>>>>>>>>>EmiAfter Full Game:Rin>>>>>>>>>Hanako>>>Shizune>>>Lilly>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>EmiCome at me, bros.

Im reviving this old thread ;DAnyways, Doubt this will ever be answered, But are you planning on making the Characters downloadable at some point? I'm in NO way creative enough to make them on my own xD